Apparatus and method for the conversion of thermal energy sources including solar energy

ABSTRACT

Systems and methods to efficiently utilize thermal energy such as solar energy, geothermal energy, waste-heat energy, bio-mass combustion energy, or other equivalent forms of energy, convert the thermal energy to another useful form of energy, such as electricity or mechanical work using a thermodynamic cycle in which a working fluid medium may be expanded in a constant pressure environment to move a storage medium comprising another fluid, slurry or mass to a higher potential energy level, from which the storage medium may be released through a generator or the like to produce another form of energy.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. provisional patentApplication No. 60/735,056, filed Nov. 8, 2005, and U.S. provisionalpatent Application No. 60/737,682, filed Nov. 17, 2005, the disclosuresof which are hereby incorporated by reference herein.

TECHNICAL FIELD

The invention relates generally to energy conversion systems andmethods, and more particularly to the conversion of solar and similarforms of heat energy to other forms of energy.

BACKGROUND

There are several sources of relatively abundant, relatively inexpensivelow density thermal energy, such as solar energy, geothermal energy,waste-heat energy, and equivalent types of low energy density heatenergy. Conversion of this thermal energy to other forms of more usefulenergy, while desirable to meet today's increasing energy demands andcosts and because of environmental reasons, has not been widely usedbecause it has been relatively expensive and inefficient. Solar energyhas a relatively low power density, typically providing an average of4-6 kilowatts per square meter per day for a given flat surfacecollector area in the continental USA, and conventional approaches toincrease energy production have focused on the use of very large arraysof mirrors or lens systems to concentrate the photon energy of solarradiation, which are problematic.

The problems with very large arrays include the installation and landcost, vulnerability to high winds, dust and sand damage to mirrors andlenses, and the traditional maintenance costs for both tracking systemsand the lens/mirror systems. Mirror and/or lens systems are alsosusceptible to degradation over time, and the tracking equipment to keepthe mirror and/or lens properly positioned in correspondence with themovement of the sun is complex and costly to maintain.

Conventional generation of electricity from solar energy has also hadseveral serious problems. One common method to generate electricity fromsolar energy is the use of photovoltaic cells (“PV”). However,conventional PV systems typically use less than 30% of the solar lightfrequency spectrum, that is photons having a wavelength above thatneeded to create hole-electron pairs in a PV cell. Therefore only afraction of the total solar energy is converted to electricity, and theefficiency of converting solar energy into usable power fromphotovoltaic cells is fairly low, requiring either very large surfaceareas or solar energy concentrators. The photovoltaic cells also degradeover time and lose most of their DC electricity production efficiency,typically there is a significant decrease in output after 20 years orless. Since most electrical power is AC, inverters are required toconvert the DC electricity from the photovoltaic cells to ACelectricity, and these electrical inverters have relatively short meantimes between failures, typically requiring repair within five years orless. In a current study of energy usage in California, for example,only about 0.5% of the useable energy comes from solar energy, as thecost of a solar PV KWH of electricity is on the order of 10 timesgreater than that from fossil fuel.

An alternative to photovoltaic systems is to utilize thermally poweredheat engines operating on various thermodynamic cycles (e.g., an organicRankine or other similar cycle). Thermally powered engines can generallyuse fluids to both absorb the heat from a heat source (e.g., solarenergy, geothermal energy, waste-heat energy, bio-mass combustion, andother such types of energy) to create a gas, and use high pressure gasto drive some sort of mechanical device or expander. The fluids can be asingle fluid, or a mixture of two or more fluids such as a binarysolution of ammonia and water, or the like. However, such systems havenot been found to be cost effective for large scale use. Because of thegenerally low temperature differential between the hot side of an engineand a condenser, conventional thermal power engines suffer from lowefficiency in energy conversion, expensive equipment and materials,unreliability for long-term operation, and costly maintenance.

There are three main types of passive thermal energy collector systemsused for collecting thermal energy (e.g., solar energy, or anequivalent). Low-temperature collectors (unglazed) normally operate atup to approximately 18 F° (10 C°) above ambient temperature, and aremost often used for heating swimming pools. Often, the pool water iscolder than the air, and insulating the collector would becounter-productive. Low-temperature collectors are typically extrudedfrom polypropylene or other polymers with UV stabilizers. Flow passagesfor the pool water are molded directly into the absorber plate, and poolwater is circulated through the collectors with the pool filtercirculation pump. Swimming pool heaters typically cost from $10 to$40/ft² (based on 2004 prices).

Mid-temperature collectors are usually flat plates insulated by alow-iron cover glass and fiberglass or poly-isocyanurate insulation.Reflection and absorption of sunlight in the cover glass reduces theefficiency at low temperature differences, but the glass is required toretain heat at higher temperatures. A copper absorber plate with coppertubes welded to the fins is typically used. In order to reduce radiantlosses from the collector, the absorber plate is often treated with ablack nickel selective surface, which has a relatively high absorptivityin the short-wave solar spectrum, but a relatively low-emissivity in thelong-wave thermal spectrum. Mid-temperature collectors typically rangein cost from $90 to $120/ft² of collector area (based on 2004 prices).

High-temperature collectors utilize evacuated tubes around a receivertube to provide high levels of insulation and often use focusing curvedmirrors to concentrate sunlight. High temperature collectors arenormally used for absorption cooling or electricity generation, but arealso sometimes used for mid-temperature applications, such as commercialor institutional water heating as well. Evacuated tube collectorsthemselves typically cost about $75/ft², but use of curved mirrors andeconomies of scale get this cost down for large system sizes to arelatively low cost of $40-70/ft² of collector area (based on 2004prices).

A need exists for a higher efficiency, lower cost systems for thermalenergy conversion and utilization, in general, and especially for theutilization of solar energy that avoid the foregoing and other problemsof known approaches. There is a need for systems that do not requireexpensive equipment, materials, or maintenance, are relatively stableand non-degradable in long-term operation, and have good efficiency. Itis to these ends that the present invention is directed.

SUMMARY OF THE INVENTION

The invention affords a system and method which use the phasetransformation of a working expansion medium (e.g., a liquid, or a solidsuch as dry ice) into a gas during heat absorption. During expansion,the enthalpy of the system is the physical work done plus the work ofthe latent heat of fusion which is used to change the liquid to a gas.This increases the internal energy of the system, which may be recoveredduring a cooling period, such as night time, when the gas is cooled andreturned to the liquid state and the heat evolved is emitted into deepspace on the dark side of the planet which is not facing the sun. Thiscycle creates a change in the solar cross section of the planet, as allenergy that is captured by phase transformation from liquid to gas overa given absorption area is released into space by black body radiationduring the night time operations. Energy systems in accordance with theinvention, if utilized on a large scale, can efficiently produce energysuch as electricity or other forms of useful power and power storage, aswell as help to reduce global warming.

Advantageously, the invention may provide a heat energy conversionsystem that is coupled to the normal varying, more or less sinusoidal,energy field that characterizes the daily solar heat cycle due to thedaytime exposure to the sun and the subsequent nighttime exposure to acold heat sink (e.g., deep space). This cycle comprises a heat energysource (or photons which can be converted to heat) and an energy sink.The energy source may be the sun (in the case of the planet earth) andthe energy sink may comprise interstellar space (deep space on the sideof the earth not facing the sun). A portion of heat energy absorbedduring daylight may go directly into generating external work via aprime mover, and the rest of the absorbed heat may be used to raise theenthalpy (or internal energy) of the system. The energy that goes intodriving an expansion medium, i.e., a working fluid or working liquid, tothe gas phase raises the internal energy of the system. This energy canbe stored in the system and can be emitted via black body radiation todeep space on during nighttime operations. Heat is not absorbed by thesystem, rather it passes through the system, is absorbed in theliquid-to-gas phase transformation, and then is emitted in thetransformation of the expansion medium from gas to liquid.

The invention may utilize, in part, the fact that when an expansionfluid makes the transformation from a liquid to a gas, the volumeoccupied by the expansion fluid may increase by several, typically aboutthree; orders of magnitude (1000 times larger). The liquid-to-gastransformation is done with the liquid at a high pressure, as will beshown later on the pressure vapor curve for the expansion fluid. Heat issupplied by the sun to drive the temperature of the expansion fluid tothe boiling point and then into the liquid-to-gas transformation. As thevolume of gas increases, this volume change can be used to displaceanother working medium, referred to as a storage medium, to a higherpotential energy. Once the storage medium is at the higher potentialenergy it can either be used directly being returned to a lowerpotential through a prime mover which extracts energy from the storagemedium, or it can be stored at the higher potential energy level for useat some later time.

The invention can be used to pump a working medium, such as water, to ahigher potential energy and transport it over a hill such as theCalifornia aqueduct passing over the Grapevine area of California, whereit can be available for different uses. In this case the working medium(water) can be replaced on the pumping side by water flowing in theCalifornia aqueduct from Northern California to Southern California

The invention also affords a pixelized collection system to allow formore efficient use of the absorbed heat energy, and enables use of cellsthat have been fully expunged of the working medium by the gaseousexpansion medium to heat the liquid expansion medium for subsequentcells in the pixelization collector, thus increasing the overallefficiency of the system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a block diagram of a conventional Rankine cycleengine, as used in conventional solar energy applications;

FIG. 2 illustrates a block diagram of a modified Rankine cycle inaccordance with one embodiment of the invention;

FIG. 3 illustrates a vapor pressure curve of an expansion medium, suchas ammonia, that may be used in the invention;

FIG. 4 is a block diagram of a thermal energy system in accordance witha first embodiment of the invention;

FIG. 5 is a more detailed block diagram of the system shown in FIG. 4;

FIG. 6 is a diagrammatic view of an implementation of a thermal energysystem in accordance with the invention;

FIG. 6A is a diagrammatic view of a thermal energy system in accordancewith an alternative embodiment of the invention where energy productionis only required during day light hours and high potential energystorage is not used;

FIG. 7 is a flowchart of a method in accordance with the embodiment ofFIGS. 4-6, 6A for converting thermal energy to another useful form ofenergy;

FIG. 8 is a flowchart of another method in accordance with the inventionfor converting thermal energy to another form of energy in a pixilationsystem of the type illustrated in FIGS. 15A-C;

FIG. 9 illustrates a flowchart of a method of generating energy, inaccordance with another embodiment of the invention;

FIG. 10 illustrates a flowchart of a method of generating electricity,in accordance with a further embodiment of the invention;

FIG. 11 is a diagrammatic view of the solar energy generation systemshown in FIG. 6;

FIG. 12 is a diagrammatic view of a solar pumping system in accordancewith the invention;

FIG. 13 is a cross-sectional view of a containment assembly that may beused in the systems of the invention;

FIG. 14 is a diagrammatic view of another embodiment of a containmentassembly, partially broken away, that may be used in the systems of theinvention;

FIG. 15A is a block diagram of a pixelized energy collection system inaccordance with another embodiment of the invention.

FIG. 15B is a more detailed diagrammatic view of a pixelized energygeneration system in accordance with another embodiment of the inventionhaving two or more interconnected energy generator assemblies;

FIG. 15C illustrates a diagrammatic view of an alternative embodiment ofthe system of FIG. 15B;

FIG. 16 is a flowchart of a method of converting thermal energy toanother useful form of energy from a plurality of interconnected energygenerator assemblies; and

FIG. 17 illustrates a fractal solar energy collector array that may beemployed for the pixelized collection of energy in accordance with theinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the invention can be constructed from commerciallyavailable components. In all of the embodiments disclosed below, variousdifferent materials may be used for the chambers, reservoirs, andpiping, including but not limited to various plastics, rubbers, resins,ceramics, cements, and metals, or other equivalent man-made materials.The collector may be a low-temperature collector, a mid-temperaturecollector, a high-temperature collector, or a combination of differenttypes of collectors.

The invention employs a working medium, also referred to as an expansionmedium, and a storage medium. The expansion medium and storage medium ofthe invention preferably comprise fluids, as will be explained. Thesetwo fluids may be the same, or one fluid may be used as the expansionmedium and a second different fluid may be used as the storage medium.Materials that may be utilized for the working (expansion) fluid andstorage fluid include, but are not limited to, acetone, alcohol, water,various water solutions, ammonia and water solutions (e.g., such as an80% ammonia and 20% water solution, or equivalents), liquefied naturalgas (LNG), chloro-fluorocarbon (CFC) refrigerants (e.g., R-410A, R-22,R-32, R-125, R-407C, R-134A), the equivalent hydrogenated CFC (HCFC)refrigerants, ammonia, carbon dioxide, or other non-aqueous fluidshaving similar vapor pressure curves. Preferred criteria for selectingthe expansion and storage media will be explained in connection withFIG. 3. Additionally, as will also be explained, the storage medium mayalso comprise a slurry, a powder, or a solid mass that can betransformed to a higher potential energy.

The invention affords a system for generating useful mechanical power,for generating chemical energy or for supplying chemical fuels (e.g.chemical fuels generated from electrolysis, e.g., hydrogen and oxygen,or equivalents), or connected to one or more electrical generators forproducing either AC or DC electricity. The invention may also be used togenerate cryogenic fluids such as liquid nitrogen. Some embodiments ofthe invention can accommodate variations in the heights available forutilizing a storage medium, if necessary.

The invention has some similarities to a Rankine cycle engine and to aSterling engine, but differs in several significant ways. First, theinvention may utilize a substantially constant pressure and a changingvolume of a working medium, e.g., a fluid, the volume increasing duringan expansion phase and decreasing during a contraction phase, to produceuseful work. Work may be extracted by a corresponding increase in thevolume of a displacement chamber, for example, caused by the conversionof a liquid expansion medium to a gas. This expansion ratio of gas toliquid may be on the order of 1000 times the volume in the gas phaseverses the liquid phase.

FIG. 1 illustrates a block diagram of a conventional Rankine cycleengine. As shown, there is a boiler 102 connected with a pipe 169 to aturbine 112, which is connected with an output pipe 167 to a condenser124. The condenser is connected with an output pipe 165 to a feed pump106 that supplies boiler 102 by an output pipe 104. The expansion mediumin a conventional Rankine cycle engine is typically water.

The turbine 112 (e.g., a steam turbine, water turbine, or generator)utilizes a substantially isentropic expansion; the condenser 124utilizes a substantially isobaric heat rejection; the feed pump 106utilizes a substantially isentropic compression; and the boiler 102utilizes a substantially isobaric heat supply. Heat 103 is supplied tothe boiler 102 and heat 105 is rejected by the condenser 124. The workoutput 107 is from the turbine and the work input 108 is to the feedpump 106. The net work produced by this engine is the difference of thework output 107 and the work input 108.

In a conventional Rankine cycle engine, work is extracted by expanding ahigh pressure gas (and volume) and reducing the gas pressure during thisexpansion cycle. Unlike a Rankine cycle, as will be explained, theinvention does not have to expand the gas to a lower pressure to extractwork. It may reduce the gas temperature and volume, and heat a liquidexpansion medium to near its boiling point. The expansion of the gas maybe used to displace a storage medium from a low potential energy (“LE”)to a high potential energy (“HE”). As the storage medium is returned tothe lower potential energy, it may pass through a prime mover (e.g., aturbine, generator, pump, mechanical power take off) or other systemthat uses the energy change to produce work. Thus, while the workextracted is from the expansion of the working medium from liquid togas, the invention does not expand the gas to a lower pressure as isdone in a conventional Rankine cycle.

In addition, as mentioned above, the invention may utilize the fact thatwork is required for the transformation of a liquid to a gas, (thelatent heat of fusion or internal energy of the system), and physicalwork may be extracted as the liquid expands, typically about 1000 times,as it goes through the phase transformation at a high pressure. Thisexpansion of volume may be used to generate physical work, as in acollector/expansion system. If the collector/expansion system iscomposed of a plurality of small chambers, then when a given chamber hasall of its storage medium (the “storage medium” may be a fluid such aswater, a slurry or powder, or a physical mass that can be lifted to ahigher potential energy) displaced by the expansion medium, that chambercan be isolated from the main system's storage media, and the heattrapped in that smaller chamber can be used to raise an expansion fluidtemperature to just below the liquid-to-gas transformation temperature.The invention may employ several fully displaced chambers so that all ofthe heat energy that was used to raise the first chamber liquid to theboiling point can be recovered from the hot working medium gas.

As the temperature of the gas is lowered, the chamber can then bepartially refilled with the storage media and then reheated to forcemore storage media to a higher potential. This is similar to the reheatcycle in an advanced reheat Rankine cycle engine or somewhat like thatof a Sterling engine.

Thus, the invention differs substantially from a conventional Rankinecycle in the fact that the gas that is evolved from the expansion mediumis not expanded in an increased volume and the temperature is notlowered. Rather, the pressure can be retained at a constant value andthe volume may be expanded to contain the increased gas volume due tothe liquid-to-gas transformation of the expansion media. The increasedvolume may be used to move the working medium to a higher potentialenergy, from which it may be run through a prime mover (turbine,expander, pressurizer, etc. ) to produce work as it moves to a lowerpotential energy. The working medium may then be returned to its lowestpotential energy as it is used to pressurize the gaseous expansionmedium and help (with cooling) to drive the phase transformation of theexpansion media from the gas phase to the liquid phase. The inventionmay comprise a binary system that includes an expansion medium which isseparate from the working media, and the expansion medium drives theworking media to a higher potential energy. In addition the inventiondoes not require a conventional feed water pump as does a conventionalRankine cycle engine.

FIG. 2 illustrates a block diagram of a thermodynamic cycle of amodified Rankine cycle engine in accordance with the invention.Referring to FIG. 2 there is a reservoir 110, connected with an outputpipe 169, to a turbine (e.g., steam turbine, water turbine, generator,or equivalent) 112 with an output pipe 167 witch is connected to acondenser 124, connected with an output pipe 165 to the containmentassembly 130, may be connected by a pipe 163 to the reservoir 110. Thereis no feed pump 106 and no output pipe 104, as in a conventional Rankinecycle engine. Heat 103 may be supplied to the containment assembly 130,and heat 105 is rejected by the condenser 124. The work output 107 fromthis engine is from the prime mover 112.

The prime mover 112 (e.g., a steam turbine, water turbine, generator, orequivalent) may utilize a substantially isentropic process, thecondenser 124 may utilize a substantially isobaric heat rejection, andthe reservoir 110 in one embodiment may be filled with a storage medium(not shown) moved by pressure provided by an expansion medium (notshown). Several possible materials could be utilized for the expansionmedium and storage medium, including acetone, alcohol, water, variouswater solutions, ammonia and water solutions (e.g., such as an 80%ammonia and 20% water solution, or equivalents), liquefied natural gas(LNG), chloro-fluorocarbon (CFC) refrigerants (e.g., R-410A, R-22, R-32,R-125, R-407C, R-134A), the equivalent HCFC refrigerants, ammonia,carbon dioxide, or other non-aqueous fluids having substantially similarvapor pressure curves. Substantially the same fluid may be used for boththe expansion medium and the storage medium. The expansion medium in themodified Rankine cycle engine can be any fluid having a suitable vaporpressure curve, for example, as shown in FIG. 3 (and described below).

FIG. 3 illustrates a vapor pressure curve of an exemplary expansionmedium, ammonia, that may be used in the invention. The vertical axis302 indicates the vapor pressure of the expansion medium, and the vaporpressure curve 304 of the expansion medium is shown plotted, between thevertical axis 302 and the horizontal axis 306 indicating the temperaturein degrees Kelvin and the horizontal axis 308 indicating the temperaturein degrees Celsius.

Suitable expansion medium for the invention is preferably selected tohave a high pressure at the high temperature side of the thermodynamiccycle, and a fairly low pressure in the condensation side of the cycle.Two suitable fluids are ammonia and carbon dioxide which have pressuresof about 40-50 bar at a working temperature of about 30-40° C. aboveambient, and also have a good pressure, on the order of 10 bar, for thecondensation of gas back to liquid. Also important is the latent heat offusion vs. the expansion factor. CO₂ may have a slight advantage inefficiency as compared to ammonia in this regard.

The process of evaporation in a closed chamber will proceed until thereare as many molecules returning to the liquid as there are escaping. Atthis point the vapor is said to be saturated, and the pressure of thatvapor is called the saturated vapor pressure. Since the molecularkinetic energy is greater at higher temperature, more molecules canescape the surface and the saturated vapor pressure is correspondinglyhigher. If the liquid is open to the air, then the vapor pressure isseen as a partial pressure along with the other constituents of the air.The temperature at which the vapor pressure is equal to the atmosphericpressure is called the boiling point. The phase change of a fluid from aliquid to a vapor (and the reverse process) can be utilized in multipleways by the invention, as described below.

FIG. 4 illustrates a block diagram of a system in accordance with afirst embodiment of the invention to utilize thermal energy. The systemincludes a high potential energy reservoir 110, a turbine 112, a lowpotential energy reservoir 114, and a containment assembly 130containing the storage media 129. The system also includes a thermalenergy collector 120 connected to an expansion medium reservoir 126,which receives the expansion medium 127 from a condenser 124, which isconnected to the containment assembly 130. The expansion medium 127 iscapable of undergoing a phase change from a liquid to a vapor upon theapplication of thermal energy, and disposed to circulate through thethermal energy collector 120, the containment assembly 130 and thecondenser 124. The storage media 129 circulates through the highpotential energy reservoir 110, the turbine 112, the low potentialenergy reservoir 114, and the containment assembly 130 as a result ofdisplacement in the containment assembly 130 caused by the vaporizationof the expansion medium 129. The thermal energy collector 120 cancollect heat from one or more sources (e.g., solar energy, geothermalenergy, waste-heat energy, bio-mass combustion, and other equivalenttypes of energy).

FIG. 5 illustrates in more detail the system shown in FIG. 4. FIG. 5shows, for example, more details of the containment assembly, andincludes a plurality of valves that may be used to control the system.As shown, containment assembly 130 may have a containment assemblyinterior 116 containing the storage medium (fluid) 129, and adisplacement chamber 122 containing the working vapor 128.

Valve 143 may control the flow in the pipe between the high potentialenergy reservoir 110 and the containment assembly interior 116 in thecontainment assembly 130. Valve 142 may control the flow in the pipebetween the low potential energy reservoir 114 and the containmentassembly interior 116 in the containment assembly 130. Valve 149 maycontrol the flow in the pipe between the low potential energy reservoir114 and the containment assembly interior 116 in the containmentassembly 130. Valve 141 may control the flow in the pipe between theturbine 112 and the low potential energy reservoir 114. Valves 146 and148 may control the flow of expansion medium (working fluid) 127 betweenthe thermal energy collector 120 and the expansion medium (workingfluid) reservoir 126. Valve 147 may control the flow of working fluid127 between the condenser 124 and the working fluid reservoir 126; andvalve 145 may control the flow of working fluid vapor 128 between thecondenser 124 and the displacement chamber 122 in the containmentassembly 130.

FIG. 6 illustrates diagrammatically an implementation of the system ofFIGS. 4 and 5 in accordance with a preferred embodiment of theinvention. As will be described, the invention may be implemented as asolar energy system using natural or man-made geographical features,such as lakes, as reservoirs. FIG. 6 illustrates lakes as reservoirs.However, it may be appreciated that the reservoirs may take other forms,and that the invention may be implemented in other contexts.

As shown in FIG. 6, the system may include a high potential energyreservoir 110 (such as lake 1), a turbine 112, a low potential energyreservoir 114 (lake 2), and a containment assembly 130 (pump chamber)containing the storage medium 129 (e.g., water) in the containmentassembly interior 116. The system also includes a thermal energycollector 120 (e.g., an evaporator) connected to an expansion mediumreservoir 126 (fluid tank), which receives expansion medium 127 from acondenser 124, which is connected to the containment assembly 130. Theexpansion medium, preferably a fluid, is capable of undergoing a phasechange from a liquid to a vapor 128 (gas) in displacement chamber 122upon the application of thermal energy (e.g., from the sun 600) anddisposed to circulate through the thermal energy collector 120, thecontainment assembly 130 and the condenser 124. The storage medium(water) 129 circulates through the high potential energy reservoir 110,the turbine or prime mover 112, the low potential energy reservoir 114,and the containment assembly 130 as a result of displacement caused bythe vaporization of the expansion medium 129 in the displacement chamber122. Valves v1, v2, v3, v4, v5, v6, v7, and v8, which are analogous tovarious ones of the valves shown in FIG. 5, control the system and willbe described in detail in connection with FIGS. 11 and 12. The sun maybe the thermal energy source in this embodiment, but in otherembodiments other heat sources may be used alone or in combination tosupply the thermal energy.

Generating electrical energy in large quantities for an electrical powergrid is not trivial, especially for AC electricity power grids. Largeamounts of electricity needed by an electrical power grid cannot bestored as electricity in conventional systems, although it may be storedin another form. Therefore, the energy taken from an electrical powersupply grid must always be equal to the energy being delivered by theelectrical power plants. If this were not the case, the frequency andvoltage of the supply grid would deviate from standard values.

Pumped storage plants address this problem by storing electrical energyas potential energy. They pump water to an upper reservoir at times ofsurplus energy on an electrical supply grid-typically, at night. Thispotential energy is then released through a hydro-electrical generatorat times of high demand. Use of hydroelectric turbines allows directenergy conversion to AC electrical power. Electrical DC to AC conversion(used in many conventional solar energy systems) is not required,thereby significantly reducing the complexity, reliability problems, andcost of construction and maintenance, as compared to conventional DCelectricity supply systems.

FIG. 6A illustrates a modification of the system of FIG. 6 which is usedfor power generation during daylight operations only. In this system,the flow of the working medium (water) is not supplied to a highpotential energy reservoir, such as lake 1, but is directly input intothe inlet of the prime mover or turbine 112 to generate power, such aselectricity.

FIG. 7 is a flowchart of a method of converting thermal energy toanother useful form of energy, in accordance with the embodiment of theinvention shown in FIGS. 4-5. Referring to FIG. 7, the method begins at702. At 704, thermal energy is absorbed into an expansion medium, suchas a working fluid. At 706, at least a portion of the expansion mediumis vaporized to exert pressure on a storage medium, such as a storagefluid, to displace at least a portion of the storage fluid from a lowerpotential energy state to a higher potential energy state. Thiscorresponds, for example, to transporting the storage fluid from chamber116 of containment assembly 130 of the system of FIG. 6 to the reservoir110. At 708, the portion of the expansion fluid that was vaporized issubstantially condensed, corresponding, for example, to condensing aportion of the expansion gas 128 from chamber 122 back to a liquid incondenser 124. At 710, a portion of the storage fluid displaced to ahigher potential energy state (to reservoir 110, FIG. 6) is supplied toat least one turbine to produce a second form of energy. At 712,substantially the portion of storage fluid from the at least one turbineis supplied to at least one lower potential energy state. The methodends at operation 714.

FIG. 8 illustrates a flowchart of another method in accordance with theinvention for converting thermal energy to another form of energy in apixelized system (such as will be described in more detail in connectionwith FIGS. 15A-C) which combines the contributions of multiple energycollector/generator assemblies. The method contemplates a system thatuses of one or more expansion and storage media, e.g., fluids, as wellas multiple separate components for some system components, such asthermal energy collectors, containment assemblies, condensers, primemovers, etc. The method begins in operation 802. At 804, at least oneexpansion medium (working fluid) is stored in a working fluid reservoir.At 806, the at least one working fluid is communicated to at least onethermal energy collector to vaporize a portion of the at least oneworking fluid. At 808, the vaporized portion of at least one workingfluid is communicated into at least one containment assembly, where theportion of the vaporized working fluid exerts pressure on at least onestorage medium (fluid) in the at least one containment assembly totransport the at least one storage fluid to at least one higherpotential energy reservoir. At 810, the portion of vaporized at leastone expansion fluid from the at least one containment assembly iscommunicated to at least one condenser, where the vaporized portion ofthe expansion fluid is condensed and communicated to at least oneexpansion medium reservoir. At 812, at least one storage fluid from theleast one higher potential energy reservoir is communicated to at leastone turbine generator, where another form of energy, e.g., electricity,is generated, and at 814 the at least one storage fluid is communicatedfrom the at least one generator to at least one lower potential energyreservoir. At 816, the at least one storage media is communicated fromthe at least one lower potential energy reservoir to the at least onecontainment assembly, and the method ends at 818.

FIG. 9 is a flowchart of a method of generating energy that is somewhatsimilar to that shown in FIG. 7, except that the method is moreprecisely focused on FIG. 6. The method begins at 902. At 904, at leastone expansion medium (working fluid) is stored in an expansion mediumreservoir. At 906, the at least one working fluid is communicated to anenergy collector. At 908, the working fluid in the energy collector isvaporized and communicated into a containment assembly at 912, where thevaporized working fluid exerts pressure on a storage fluid in thecontainment assembly to transport the storage fluid to a high potentialreservoir. At 912, the vaporized working fluid from the containmentassembly is communicated to a condenser where it is condensed. At 914,the expansion medium from the condenser is communicated to the expansionmedium reservoir. Operation 916 is next and includes supplying thestorage fluid from the high potential reservoir to a generator whereenergy is generated. At 918, the storage fluid from the generator iscommunicated to a low potential reservoir, and at 920 is communicated tothe containment assembly. The method ends at 922.

FIG. 10 illustrates a method of generating electricity, in accordancewith the invention. The method begins at 1002. At 1006, working fluidstored in a reservoir is transported using gravity to a solar collectorwhere it is vaporized by solar energy. At 1008, the vaporized workingfluid is communicated into a containment assembly, where the vaporizedworking fluid exerts pressure on a storage fluid in the containmentassembly which transports the storage fluid to a high potentialreservoir. At 1010, the vaporized working fluid is communicated from thecontainment assembly to a condenser where it is condensed by heattransfer to the ambient environment. Operation 1012 is next and includesusing gravity to transport the working fluid from the condenser to theworking fluid reservoir. At 1014, the storage fluid supplied from thehigh potential reservoir to an electrical generator, whereby electricityis generated. At 1016, the storage fluid is exhausted from theelectrical generator to a low potential reservoir, and transported usinggravity to the containment assembly at 1016. The method ends at 1020.

FIG. 11 is diagrammatic view of an embodiment of an energy generationsystem 100 corresponding to that shown in FIGS. 4-6. A reservoir 126holds an expansion medium, i.e., a working fluid, 127 and may beconnected by a pipe 166 to a collector 120. A valve 146 may control theflow of expansion medium 127 between reservoir 126 and collector 120.Flow of expansion medium 127 from reservoir 126 to collector 120 may beinduced by gravity or pumping. Collector 120 is configured to increasethe temperature of the expansion medium flowing through it when exposeda source of energy, such as the sun. Once the temperature of theexpansion medium 127 in collector 120 reaches a critical temperature, itundergoes a phase change from a liquid to a vapor. The gaseous expansionmedium vapor 128 occupies a larger volume than the liquid expansionmedium 127, and it may be communicated through pipe 164 into adisplacement chamber 122 contained in the interior 116 of a containmentassembly 130. A valve 144 may control the communication of vapor 128from collector 120 to displacement chamber 122. Significantly, thedisplacement chamber 122 may be constructed, as with bellows or thelike, to increase its volume in response to increasing pressure withinthe displacement chamber so as to maintain the pressure in the chambersubstantially constant. Accordingly, as the vapor 128 expands intodisplacement chamber 122, the displacement chamber 122 increases involume. Pressure exerted by liquid working fluid in chamber 116 on thevapor in expandable displacement chamber 122 causes the vapor to flowthrough a pressure equalization line 1.68 to maintain approximatelyequal pressure between collector 120 and reservoir 126. A valve 148 maycontrol the communication between reservoir 126 and collector 120.

When displacement chamber 122 has increased by a predetermined volume,ΔV1, expansion medium vapor 128 may be conducted through a pipe 165 to acondenser 124. A valve 146 may control flow of the vapor 128 between thedisplacement chamber and the condenser. In condenser 124, the expansionmedium vapor 128 undergoes a phase change from a vapor 128 to a liquid127. In undergoing this phase change from vapor to liquid, the expansionmedium vapor 128 decreases by a predetermined volume ΔV2 in thecondenser, and displacement chamber 122 also decreases by about the samepredetermined volume ΔV2. The expansion liquid 127 may flow to reservoir126 through a pipe 167 between condenser 124 and reservoir 126 may becontrolled by a valve 147. The flow of condensed expansion liquid 127from condenser 124 to reservoir 126 may be induced by gravity orpumping.

Containment assembly 130 also contains a storage medium, e.g., a fluid,129 in the containment assembly interior 116. As displacement chamber122 expands inside of containment assembly interior 116, pressure onstorage medium 129 causes it to be displaced and communicated by a pipe163 to a high potential energy reservoir 110. A valve 143 may controlthe communication of storage medium 129 between the containment assemblyinterior 116 and the reservoir 110. Subsequently, the storage medium 129may then be communicated from the high potential energy reservoir 110through a pipe 169 to a prime mover 112, such as a generator, a turbine,or other power producing device. A valve 149 may control thecommunication of storage medium between the high potential reservoir 110and prime mover 112. Storage medium 129 may then be communicated througha pipe 161 from the prime mover to a low potential reservoir 114. Avalve 141 may control the communication of the storage medium betweenthe prime mover and the low potential reservoir. Storage medium 129 maythen be communicated through a pipe 162 from the low potential reservoir114 to the interior 116 of containment assembly 130. A valve 142 maycontrol this flow.

As discussed above, the flow of expansion medium 127 from reservoir 126to collector 120 may be induced by gravity or pumping. Placing thereservoir 126 at a higher gravitational potential than the collector120, i.e., at a higher height than the collector, enables the expansionmedium 127 to flow down under the influence of gravity from thereservoir 126 to the collector 120. Pressure equalization line 168prevents a vacuum from disrupting the flow of expansion medium betweenreservoir 126 and collector 120 by equalizing the pressure betweenreservoir 126 and collector 120.

High potential reservoir 110 is preferably placed at an elevation orheight Hi above the containment assembly 130 so that the work requiredto move the storage medium 129 from containment assembly 130 to the highpotential reservoir 110 is imparted to the storage medium as potentialenergy. At such elevation H1, the storage medium in the high potentialreservoir exerts a pressure P1 through pipe 163 at containment assembly130. The pressure P1 is determined by the height H1 of high potentialreservoir 110 above containment assembly 130. For example, when thestorage medium 129 is water, the pressure P1 is about 0.43 pounds persquare inch for each foot of height H1. For a height H1 of about 1300feet, the pressure at the containment assembly 130 will be about 560pounds per square inch (560 psi).

The minimum amount of work, W, required to raise a predetermined mass M1of storage medium 129 from the containment assembly 130 to the highpotential reservoir 110 is simply the mass M1, times the height H1,times gravitational acceleration g, or:W=M1*g*H1   (1)

The storage media 129 in high potential reservoir has a potential energyequal to the work W. This potential energy is available for conversionto some other form of energy, for example electricity. For example, aportion of this potential energy may be used to operate the prime mover112. The prime mover 112 may be placed a distance H2 below the highpotential reservoir 110, so that the amount of potential energy Eavailable to operate generator 112 may be calculated as thepredetermined mass M2 of the storage medium released to the prime mover112, times the distance H2, times g or:E=M2*g*H2   (2)

While a generator is an example of a prime mover that may be used, otherforms of energy conversion apparatus may also be utilized to advantage.For example, mechanical energy may be extracted from the potentialenergy E in a variety of ways well known in the mechanical and hydraulicarts.

Moreover, storage medium 129 could also be used to raise a mass otherthan the storage medium 129 to the high potential reservoir 110. Forexample the storage medium could be employed to provide power othertypes of mechanical and hydraulic apparatus adapted to lifting adiscrete object, or solid mass (such as rock or grain, for example) tothe high potential reservoir.

As indicated above, the temperature of expansion medium 127 rises incollector 120 until the critical temperature of the expansion medium isreached. The critical temperature of a fluid is the temperature at whichthe fluid will undergo a phase change from fluid to vapor at the ambientpressure. For example, the critical temperature of a common refrigerantR-410A is about 150 degrees F. at an ambient pressure of 550-600 psi.The ambient pressure in the interior 116 of containment assembly 130 maybe the pressure P1, as determined by the elevation H1 of the highpotential reservoir 110 above the containment assembly 130. Asindicated, when elevation H1 is about 1300 feet the pressure P1 at thecontainment assembly interior will be about 560 psi and the R-410A wouldundergo a phase change from fluid to vapor at about 150 degrees F. Atthe critical temperature, additional heat energy (for example heatenergy from solar energy) applied to the collector 120, causesadditional molecules of the expansion medium to undergo the transitionfrom fluid to vapor without increasing the temperature of the expansionmedium above the critical temperature. R-410A is given by way of exampleas a suitable expansion medium, but many other types of expansion mediamay be used, as previously described.

As discussed above, when displacement chamber 122 has expanded to apredetermined volume, the expansion medium vapor 128 in displacementchamber 122 may be conducted through a pipe 165 to a condenser 124.Condenser 124 may be maintained at a temperature substantially below thetemperature of the collector 120 during the expansion of the expansionmedium fluid into a vapor. At a lower temperature, the expansion mediumwill condense at a substantially lower pressure. Storage medium 129 inlow potential reservoir 114 may be used to displace expansion mediumvapor 128 from displacement chamber 122 through pipe 165 into condenser124. A pressure P2 may be exerted through pipe 162 to compressdisplacement chamber 122 and exert a pressure P2 on the expansion vaportherein. The pressure P2 may be determined by the elevation H3 of thelow potential reservoir 114 above the containment assembly 130. Forexample, when elevation H3 is about 230 feet, pressure P2 may be about100 psi. At about 90-120 psi, R-410A vapor will condense at about 50degrees F., for example.

The available work, Wa, from energy system 100 is the change in volumeΔV1 times the pressure P1 minus the change in volume ΔV2 times thepressure P2 or:Wa=P1*ΔV1−P2*ΔV2   (3)When ΔV1=ΔV2, the available work is:Wa=ΔV1(P1−P2)   (4)

As discussed above, the flow of expansion medium 127 from condenser 124to reservoir 126 may be induced by gravity or pumping means. Placing thecondenser 124 at a higher gravitational potential than reservoir 126,that is above the reservoir 126, enables the expansion medium 127 toflow down under the influence of gravity from the condenser to thereservoir 126.

In an example of operation of the energy generator system 100, solarenergy may be used during the day to cause expansion of an expansionfluid 127 to an expansion vapor 128. The expansion vapor may be used inthe containment assembly 130 to pump water during a pumping step up tohigh potential reservoir 110, for example a lake at a high level. Thewater may then generate electricity by running back down through aturbine during an energy generation step to low potential reservoir 114,for example to a lake at a lower level. At night, when the condenser 124has been cooled by giving off energy in the form of radiation to thesky, water in the low potential reservoir 114 may then be used torecompress the expansion vapor 128 into an expansion fluid 127 in thecondenser 124. In this case, energy may be input into the system 100during the daytime from a high energy source, e.g., solar radiation.Energy may be output from the system 100 during the nighttime into a lowenergy sink, as by radiation to a black body (e.g., into space). Theenergy source is the sun, and the energy sink is space. The energygenerator system 100 extracts useful work or electricity by moderatingthe flow of energy from the high-energy source to the low energy source.

Table 1 below illustrates examples of valve states for the system 100 ofFIG. 11 during a pumping phase, an energy generation phase and arecompression phase (either warm or cold). During conversion of heatenergy to potential energy (the pumping phase), valves 142, 145, and 147may be closed while valves 143, 144,146, and 148 may be open. During theday, solar energy heats the collector 120 and the expansion medium 127,for example R-410, expands to an expansion vapor at about 150 degrees F.at a pressure of about 550-600 psi. Expanded vapor 128 flows throughpipe 164 and open valve 144 into displacement chamber 122. Valve 145 maybe closed, thus forcing displacement chamber 122 to expand insidecontainment assembly 130. As expansion medium 127 is used up byexpansion into vapor 128, the expansion medium 127 may be replaced fromreservoir 126 through pipe 166 by opening valve 146. Placing reservoir126 above collector 120 enables gravitational flow of expansion medium127 downhill from reservoir 126 to collector 120 through valve 146.Valve 148 permits pressure equalization through pipe 168 betweencollector 120 and reservoir 126, thus enabling flow from reservoir 126to collector 120. Expansion of the displacement chamber 122 displacesthe storage medium 129, for example water. The water is forced up hillto the high potential reservoir 110 through pipe 163 and valve 143 bythe expansion of the working fluid to vapor. Valves 143 and 146 may bepartially opened to control pressures in the containment assembly 130,and may be adjusted to optimize the work extracted in lifting water tothe high elevation lake 110. Once in the lake (high potential reservoir110), the water may be released through valves 141, 149, as desired, togenerate electricity. Thus the generation step may be independent of, orcoincident with, either the pumping step or the recompression step.Valves 141 and 149 may be opened or closed as the generator may or maynot be operated during the pumping step. The following Table 1illustrates the valve states during different phases of operation ofsystem 100. TABLE 1 Expansion medium/vapor Storage Media valves state144 145 146 147 148 141 142 143 149 Pumping step 1 0 1 0 1 X 0 1 XEnergy generation step X X X X X 1 X X 1 Recompression step (warm) 0 1 01 0 X 1 0 X Recompression step (cold) 0 1 X 1 X X 1 0 Xstate: 1 = open; 0 = closed; X = open or closed

During the energy generation phase, as illustrated in Table 1 theexpansion medium, water for example, may be released through pipe 169 byopening valve 149 and valve 141. Valve 149 may be redundant but it isdesirable because it permits retaining the water in the lake withminimal pressure head on the generator 112. Valves 142, 143, 144, 145,146, 147, and 148 may be open or closed during the energy generationstep. The water may flow through generator 112, for example, a turbine,to generate electricity. Alternatively, the water may be used to performother forms of work. Open valve 141 permits water to flow through pipe161 to low potential reservoir 114, for example, a low level lake. Thewater may be stored in the low potential reservoir until time forrecompression of the expansion medium vapor 128 back into the expansionmedium 127 during the recompression step.

During the recompression phase, as illustrated in Table 1, valves142,145, and 147 may be open, and valves 143 and 144 may be closed.Valves 141 and 149 may be either open or closed. Valves 146 and 148 maybe open or closed when the recompression step is performed under coldconditions, that is when the temperature of collector 120 is about thetemperature of the condenser 124 or lower. When recompression is doneunder warm conditions, that is when the temperature of collector 120 isabove the temperature of condenser 124, then valve 146 and 148 arepreferably closed. Recompression may take place when the condenser 124reaches a substantially lower temperature than the pumping phasetemperature, for example, about 50 degrees F. At about 50 degrees FR-410A may be recompressed at a pressure of about 90-120 psi. A pressureof about 90-120 psi may be exerted by a pressure head of about 200 feet.Therefore, the low level reservoir may be located about 200 feet abovethe containment assembly 130. The recompression takes place as waterfrom the low potential reservoir 114 flows down to the containmentassembly 130 through pipe 162 and valve 142. The water urges theexpansion medium vapor 128 through pipe 165 and valve 145 to thecondenser 124. The condenser is preferably maintained at about 50degrees F. In the condenser the expansion medium vapor 128 condenses tothe expansion medium fluid 127. Condensation of the expansion mediumvapor 127 to the expansion medium fluid 128 creates a low-pressureregion in the condenser 124 that draws more expansion medium vapor 128into condenser 124 for condensation. Heat energy is released by thecondensation process.

The condenser 124 may dissipate this heat energy through a number ofmethods. For example, the recompression may be conducted at night whenthe ambient temperatures are substantially lower than during thedaylight hours. Such substantially lower temperature may be sustained byradiation from the condenser into a black body, such as a clear nightsky, i.e., into space. The condenser may also be placed in a body ofwater, such as a lake, for example. Such bodies of water may be sized toafford a good sink and accept large quantities of heat energy from thecondenser 124, thus advantageously maintaining the condenser 124 at asubstantially constant temperature. Moreover, bodies of water makeexcellent radiators into the clear night sky. In accepting heat energyfrom the condenser 124 and radiating it into a black body, such asspace, bodies of water act as heat conductors to conduct heat from thecondenser 124 to space. An example of a large body of water or lake maybe the low potential reservoir 114.

FIG. 12 is diagrammatic view of one embodiment of a solar pumping system200. The system of FIG. 12 may be substantially similar to the system100 of FIG. 11, except that instead of using a storage medium or fluid129, the system may be used to communicate a working pump fluid 229,e.g., water, from a low position reservoir 214 to a high positionreservoir 210, where the pump fluid may be stored or use, e.g., forirrigation, and the system 200 does not have a return path through aprime mover 112 (and the associated components) for energy generation asdoes the system 100 of FIG. 11.

The operation of the system 200 of FIG. 12 may be substantially the sameas that described above for the system 100 of FIG. 11. As with system100, the pump fluid 229 may also provide power to a mechanical andhydraulic apparatus, for example, to lift a discrete object or a solidmass (such as rock or grain, for example) to the location of highposition reservoir 210.

Low position reservoir 214 may be any source of pump fluid 229 which itis desired to pump to a higher location. Preferably, since pump fluid isnot returned to low position reservoir 214, the low position reservoir214 may be a source of pump fluid that is functionally unlimited, suchas a lake, an aqueduct, or a river.

The valve states during operation of the system 200 may be the same asshown in Table 1, except that there are no valves 141 and 149 in system200 since there is no return path from the high position reservoir.

FIG. 13 is a diagrammatic view of a first embodiment of a containmentassembly 130 that may be employed in systems in accordance with theinvention. FIG. 13 illustrates the expansion medium vapor 128 in thedisplacement chamber 122 separated from the storage medium 129 by apiston 310. Piston 310 may be a mechanical piston, as is well known inthe mechanical arts, or a layer of fluid adapted to form a barrierbetween storage medium 129 and expansion medium vapor 128, the fluidbeing non-miscible with the storage medium 129 and the expansion mediumvapor 128. A suitable fluid layer piston, where the storage medium 129is water, is an oil that is non-miscible with water.

As illustrated in Table 1 above, during the pumping step of the cycle,valves 143 and 144 are open while 142 and 145 are closed. Expansionmedium vapor 128 may be admitted to the interior 122 of the displacementchamber at a higher pressure than the pressure on the storage medium129, and the storage medium is displaced and exits through pipe 163 andvalve 143. During the recompression step, valves 143 and 144 may beclosed while valves 142 and 145 may be open to control flow throughpipes 162, 163, 164, and 165. Pressure from the low potential reservoir114 drives piston 310 against the expansion medium vapor 127 indisplacement chamber 122. Displacement chamber 122 decreases in volume,and the expansion medium vapor 128 exits the displacement chamberthrough pipe 165 and valve 145. As described above, the movable pistonand the operation of the containment assembly advantageously insuresthat the expansion and recompression of the expansion medium isaccomplished at substantially constant pressure.

FIG. 14 is a diagrammatic view of another embodiment of a containmentassembly 130 that may be used in the invention. FIG. 14 illustrates theexpansion medium vapor 128 in the displacement chamber 122 which isseparated from the storage medium 129 by a moveable piston 310. As withFIG. 13, piston 310 may be a mechanical piston or a layer ofnon-miscible fluid adapted to form a barrier between storage medium andthe expansion medium vapor. The piston 310 separates the expansionmedium vapor 128 from the storage media 129 and preventing mixing of thefluid 129 with the vapor 128. When piston 310 is a layer of fluid, suchas oil, the piston has the added advantage of being capable of sealingcomplex or irregular interior surfaces of the containment assembly.

Tube 170 may communicate the storage medium 129 from the containmentchamber 130 through a single orifice in the containment chamber wall tovalves 142 and 143, thus preserving the structural integrity ofcontainment chamber 130. Similarly, tube 171 may communicate theexpansion medium vapor 128 to the containment assembly through pipes 164and 165 controlled by valves 144 and 145, respectively.

Pixelization of Energy Collection for Energy Concentration

Conventional thermal energy conversion systems typically concentrate thethermal energy in one location so that one central converter cantransform the thermal energy into another useful form of energy such aselectricity. The invention advantageously enables a different approach,referred to herein as “pixelization”, whereby multiple dispersed energyconversion systems (or portions thereof) such as previously describedmay be combined into a single system that effectively sums theindividual contribution of each individual system. Pixelization inaccordance with the invention may accomplished by moving storage media(e.g., water, or another storage media) from point to point rather thanby moving the thermal energy to a central site. This movement of thestorage medium from many dispersed collectors to a central collectionsite, for example, allows for the collected energy to be concentrated byadding the output of multiple fluid pumps of lower capacity, and reducesthe need to transport heat over large distances to a central evaporator.Multiple evaporators can be positioned close to the solar collectors.Also, pixelization allows for the full displacement of a given chamber'sworking medium by hot gaseous expansion of the medium, and the use ofthe hot gaseous expansion to preheat liquid expansion medium that willbe boiled off (converted to vapor, as described above) to evacuate otherchambers of their working medium. Using several chambers in sequencewill allow almost all of the heat energy that was used to raiseexpansion medium in a first chamber to the boiling point to be capturedand reused, thus increasing system efficiency substantially. Also,because the chambers that have been used for heat exchange have a lowerpressure, they can be partially refilled with working medium andreheated to drive even more working medium to a higher potential energypoint.

FIG. 15A is a block diagram of a system for the pixelized collection ofenergy, in accordance with the invention. A plurality of energygenerator assemblies 100′a-n may move a storage medium through amanifold 510 to a high potential energy reservoir 110. Moreover, thetransformation of thermal energy to another form of energy can beperformed by multiple units at dispersed localized locations, and thetransformed energy (e.g., the movement of a storage medium, such aswater, to a higher elevation) from the dispersed units may betransported and added together at one or more other locations to takeadvantage of economies of scale in the transformation of potentialenergy into electrical energy, or in pumping or refrigerationapplications.

A principal advantage with this system is that the losses associatedwith the transportation of low heat differential masses are minimized,and the savings are transformed into the increase in potential energy ofthe storage medium. Individual pixelization units can also be run usingstandard Rankine cycle pumps. Moreover, standard Rankine cycle pumps canbe used in a first group of pixelization units, and modified Rankinecycle pumps of the invention, such as shown in FIG. 2, can be used in asecond group of pixelization units and their energy contributionscombined.

FIG. 15B is a diagrammatic view of an embodiment of a pixelized energygeneration system in accordance with the invention that comprises aplurality of two or more interconnected energy generator assemblies100′a-n that have a common manifold 510 for receiving and combining thepump storage media from the individual generator assemblies 100′a-n. Theenergy generator assemblies 100′a-n may be placed in dispersed locationsor collocated in an array. Each of the energy generator assemblies100′a-n produces a partial contribution to the total combined energyfrom the group of generator assemblies which is combined at the manifold510 with the partial contributions from other generator assemblies. Thepartial energy generated by each of the energy generator assemblies100′a-n may be proportional to the area of sunlight striking the energygenerator assembly. The manifold 510 may communicate the combined energyto a high potential reservoir 110 through a pipe 163, where thecontribution of each energy generator assembly 100′a-n may beaccumulated.

FIG. 15C is a diagrammatic illustration of an alternative embodiment ofan energy generation system similar to that shown in FIG. 15B, exceptthat instead of a common manifold, the partial contributions of theindividual energy generator assemblies 100′a-n are separatelycommunicated to the high position reservoir 110 by separate lines 163a-n, each controlled by a corresponding valve 143 a-n. The system ofFIG. 15C is more appropriate where the various energy generatorassemblies 100′a-n are dispersed to different locations, and it is moreefficient to separately provide storage media for the individualassemblies to the reservoir than to combine the storage media in acommon manifold as in FIG. 15B

As discussed above, in both of the embodiments of FIGS. 15B and C,storage media 129 may released through a generator 112 to flow to a lowpotential reservoir 114, and the storage media from the low potentialreservoir 114 through pipe 162 and distributed through manifold 514through valves 142 a-n to energy assemblies 100′a-n. Thus, energygenerator assemblies 100′a-n may advantageously be a large number ofsmall generator systems distributed over a large area, and may be builton a small-scale with the economy of large-scale generators andreservoirs. This permits concentration of partial energy from many smallenergy generator assemblies 100′ composed of modest part sizes optimizedto exploit economies of mass production, and that may not even be inline of sight of each other. For example, energy generator assemblies100′a-n that are separated by buildings or terrain such as terrainincluding one or more hills or bluffs may still contribute energy to thesystem through plumbing connected to the reservoir 110. Thus, energygenerator assemblies 100′a-n are capable functioning in terrain wheremirror systems for concentrating solar energy might be impracticalbecause the line of sight is blocked. Moreover, energy generatorassemblies 100′a-n that are spread over a large or irregular area,beyond the practical range of a lens concentrating system, may stillcontribute substantial energy to the system through plumbing connectedto the reservoir 110.

FIG. 16 is a flowchart of a method of converting thermal energy toanother useful form of energy, in the systems of FIGS. 15A-C. The methodbegins at 1602. At 1604, thermal energy may be absorbed into anexpansion medium at a plurality of energy generator assemblies. At 1606,at least a portion of the Expansion medium may be vaporized to exertpressure on a storage medium to displace at least a portion of thestorage medium at the plurality of energy generator assemblies.Operation 1608 is next and includes condensing substantially the portionof the expansion medium that was vaporized. At 1610, the displacedportion of the storage media from the plurality of energy generatorassemblies may be collected. At 1612, the displaced portion of thestorage medium displaced to a higher potential energy state is suppliedto power at least one turbine to produce a second form of energy. At1614, substantially the portion of storage media from the at least oneturbine is supplied to a lower potential energy state. The method endsin operation 1616.

FIG. 17 is a diagrammatic view of a fractal solar energy collector arraythat may be used in the above systems for the pixelized collection ofenergy. The fractal solar energy collector 1710 may comprise arrays of aplurality of solar energy collectors 1702, arranged in a fractal patternof, for example, sixteen collector groups 1704, arranged in a fractalpattern of, for example, sixty-four collector groups 1706, all connectedto a fractal expansion medium transport system 1708.

A fractal solar energy collector array as shown in FIG. 17 may beadvantageously dispersed across a landscape for the pixelized collectionof energy, and connected to natural or man-made reservoirs or lakes forthe storage and release of storage medium through one or moregenerators, or in the case of pumping systems, for the transport ofwater, for example, through aqueducts or the like.

Refrigeration and Generation of Cryogenic Fluids

As described in the foregoing, the invention may use a prime mover suchas turbine or a generator to transform thermal energy to a second formof energy. The turbine may comprise a compressor in a refrigeration orair conditioning system, thus affording solar refrigeration and airconditioning systems, or may be used as part of a multiple stagerefrigeration system to generate cryogenic fluids (e.g., liquidnitrogen, liquid air, liquid oxygen, etc.). The compressor can be aconventional closed-loop heat pump arrangement to compress a gas whichis allowed to expand at another location and absorb thermal energy forthe expansion to cool an object (e.g., the inside of a refrigerator, oran equivalent space). Cryogenic temperatures can be reached by amultiple stage implementation of heat pumps, and the cryogenic fluids(e.g., liquid nitrogen, liquid oxygen, etc.) may be used locally ortransported to other locations for use in any of a variety of differentapplications (e.g., transportation, energy generation, various chemicalprocesses, or equivalents).

As will be appreciated, while the invention has been described withreference to preferred embodiments, various changes in these embodimentsmay be made without departing from the spirit and principles of theinvention, the scope of which is defined in the appended claims.

1. A method of converting thermal energy, comprising: supplying thermalenergy to a working medium to cause expansion of at least a portion ofthe working medium at substantially constant pressure; imparting energyto a storage medium using said expansion of the working medium to changethe energy state of the storage medium from a low potential energy to ahigher potential energy; and removing thermal energy from the workingmedium to return said working medium to a non-expanded state whilemaintaining said substantially constant pressure.
 2. The method of claim1, wherein said supplying comprises supplying solar energy to saidworking medium, and said removing comprising transferring heat from saidworking medium to an energy sink.
 3. The method of claim 2, wherein saidsupplying comprises passing said working medium through a solarcollector during daylight hours, and said removing comprises cooling theworking medium in a condenser during nighttime hours.
 4. The method ofclaim 1, wherein said working medium comprises a working fluid, and saidsupplying comprises expanding said working fluid to a gas in a containerhaving a changing volume so as to maintain the gas at said substantiallyconstant pressure.
 5. The method of claim 4, wherein said supplyingcomprises supplying additional thermal energy to the gas to increase theenthalpy of the gas.
 6. The method of claim 4, wherein said removingthermal energy from said working medium comprises using said removedthermal energy to preheat another working medium in another changingvolume container of a pixelated system to promote expansion of saidother working medium.
 7. The method of claim 4, wherein said workingfluid is selected from the group consisting of acetone, alcohol, water,various water solutions, ammonia and water solutions, carbon dioxide,liquefied natural gas (LNG), chloro-fluorocarbon (CFC) refrigerantsR-410A, R-22, R-32, R-125, R-407C, R-134A, and HCFC refrigerants.
 8. Themethod of claim 4, wherein said removing thermal energy comprisescooling the expanded working fluid while reducing the volume of saidcontainer so as to maintain said substantially constant pressure withinsaid container.
 9. The method of claim 4, wherein said imparting energyto said storage medium comprises applying energy to said storage mediumusing the changing volume of said container.
 10. The method of claim 1,wherein said converting comprising supplying at least a portion of thehigher potential energy storage medium to a prime mover at a lowerpotential energy level to convert said higher potential energy toanother form of energy using said prime mover.
 11. The method of claim10, wherein said prime mover comprises a generator, and said other formof energy comprises electricity.
 12. The method of claim 10, whereinsaid prime mover comprises a compressor in a refrigeration system, andsaid other form of energy is used to produce a cryogenic fluid.
 13. Themethod of claim 1, wherein said imparting energy to said storage mediumcomprises displacing said storage medium to an elevated height.
 14. Themethod of claim 13, wherein said storage medium comprises a fluid, andsaid displacing comprises pumping said fluid to a reservoir at saidelevated height.
 15. A method of converting thermal energy to anotherform, comprising: supplying thermal energy to a working fluid in aplurality of container assemblies having changeable volumes so as tocause expansion to a gas at a substantially constant pressure of atleast a portion of said working fluid in some of said plurality ofcontainer assemblies; removing thermal energy from the gas in one ormore of said container assemblies to condense said gas back to saidworking fluid while maintaining said substantially constant pressure;supplying a portion of said removed thermal energy to working fluid inother ones of said container assemblies to preheat the working fluid insaid other ones of said container assemblies to promote expansion of theworking fluid therein to a gas; and imparting energy to a storage mediumusing said expansion of working fluid to a gas to change the energystate of said storage medium to a high energy level.
 16. The method ofclaim 15, wherein said supplying thermal energy comprises supplyingsolar energy from a plurality of solar collectors, at least one solarcollector being associated with one or more of said containerassemblies; and said removing thermal energy from said gas comprisescondensing said gas back to said working fluid using a plurality ofcondensers, at least one condenser being associated with one or more ofsaid container assemblies.
 17. The method of claim 16, wherein saidpluralities of solar collectors, container assemblies and condensers aredispersed over a landscape, and wherein said imparting energy to saidstorage medium comprises transporting said storage medium to a storagereservoir at an elevated level above said pluralities of solarcollectors, container assemblies and condensers.
 18. The method of claim17 further comprising supplying at least a portion of said storagemedium from said reservoir to a prime mover at a lower level to converta portion of the high energy of said storage medium to another form ofenergy from the prime mover.
 19. The method of claim 18 furthercomprising returning storage medium from said low level to saidcontainer assemblies to maintain said substantially constant pressure onsaid working fluid.
 20. The method of claim 16, wherein said supplyingsolar energy comprises supplying heat to the working fluid duringdaylight hours, and said removing of thermal energy comprises condensingsaid gas during nighttime hours.
 21. The method of claim 15, whereinsaid storage medium is selected from the group comprising fluids,slurries, and solid masses.
 22. Apparatus for converting thermal energy,comprising: a solar collector for supplying solar energy to an expansionmedium circulating therethrough; a containment assembly having first andsecond chambers with changeable volumes, said solar energy causingexpansion to a gas at substantially constant pressure of said expansionmedium from said solar collector within the first chamber, the secondchamber of said containment assembly containing a storage medium, andsaid changing volumes imparting energy to the storage medium to move thestorage medium to a high potential energy reservoir; a condenser forremoving heat energy from said gas from said first chamber, whilemaintaining said substantially constant pressure, to convert the gasback to said expansion medium; and a prime mover for converting energyfrom said storage medium in said high potential energy reservoir toanother form upon said storage medium moving to a low potential energyreservoir.
 23. The apparatus of claim 22, wherein said containmentassembly comprises a container having a moveable separator thereindividing the container into said first and second chambers, the volumesof said chambers changing in relation to the movement of said moveableseparator.
 24. The apparatus of claim 23, wherein said expansion mediumand said storage medium respectively comprise an expansion fluid and astorage fluid, and said moveable separator comprises a layer ofnon-miscible fluid that moves in response to pressure changes betweenthe first and second chambers to change the volumes of said chambers.25. The apparatus of claim 24, wherein the expansion of said expansionfluid to said gas in the first chamber increases the volume of the firstchamber and decreases the volume of the second chamber and exertpressure on said storage fluid in the second chamber to displace saidstorage fluid to said high potential energy reservoir.
 26. The apparatusof claim 23, wherein said solar collector comprises a fractal array of aplurality of solar collector units arranged in collector groups, and atransport system connecting said plurality of solar collector units forconveying expansion medium through said units.
 27. The apparatus ofclaim 26, wherein there are pluralities of containment assemblies andcondensers connected to said fractal array of solar collector units toform a pixelized energy conversion system, one or more of saidcontainment assemblies, condensers and collector units being associatedtogether to form corresponding pluralities of energy generatorassemblies of said system.
 28. The apparatus of claim 22, wherein saidenergy conversion units of said system are dispersed across a landscape,and said high potential energy and said low potential energy reservoirscomprise lakes.